Multiple light-cell transmitter



Sept. 6, 1927. 1,641,633

C. F. JENKINS MULTIPLE LIGHT CELL TRANSMITTER Filed April 1. 1925gwuewtoz l d inthe broadcasting Patented Sept. 6, 192?.

PATENT OFFICE.

CHARLESIBANCIS JENKINS, OF- WASHINGTON, DISTRICT OF COLUMBIA.

MULTIPLE LIGHT-CELL TRANSMITTER.

. Application fled April 1, 1925. Serial No. 19,911.

This invention relates to apparatus emmotion' pic- ,tures and the like,and has for its main object means for increasing the eflicienc'y of thelight-sensitive cells used in such apparatus.

In the analysis of an active scene or picture for visual radiobroadcasting, the scene or picture is, in imagination, though notactually, divided into little squares of equal number each way we squarepicture. For example, in a ten inch square picture with an imaginarydivision of 50 lines per inch each way there would be 250,000' littlesquares. To make up a surface the squares would e divided again, theincreased number of sub-divisions being a varying quantity as themovingscene or picture changed. Obviously the light sensitive cell whichanalyzes this scene must respond to the light changes just described,and must recover its initial condition just as quickly. A cell which hasa lag, that is, does not recover sensitivity as quickly as it initiallyacts, is no more useful than a sluggish-acting cell. And this has beenone of the serious obstacles to a more rapid development of radiomovies; for while a single cell will respond over a considerable rangeof frequencies, the lag in recovery of the cell makes the high-frequencychange in current very minute, so-small at higher frequencies that it isalmost impossible to amplify it because it is overridden by tube noises.

' Several different types of light cells re-.

spond fast enou h, but as no cell known to applicant is without recoverlag, the fol veloped to avoid'the results of lag in recoveringsensitivity. v

With this and other objects in view the invention consists in the noveldetails of assembly of the various devices employed, hereinafterdisclosed, and particularly pointed out in the claims.

In the drawings, Fig. 1 is a schematic illustration of the invention,and Figs. 2 and 3 detail parts. In the figures A is a source of lightlocated in front of an apericture over this.

lowing method and mechanism has been de-' ture B in the mask C. Inalignment with the light source and the aperture is a small mirror Dmounted upon a rotatable shaft E at a 45 angle to the axis of a shaft.Upon the opposite end of the shaft is a single con- M tact disc F whichin rotation shifts the current of battery G alternatel to light cell Hand H, H, and H; and through each in succession to the tube K, the firsttube of an amplifier circuit. The sensitivity of most cells ispractically instantaneous and with the recovery time known, it is eas todetermine the number of cells require to take care of the entire lag ofeach cell. That is, whether two,

three, four, or more cells are desirable.

It is believed that, the object sought and the method of obtaining itunderstood, the operat1on of the apparatus will be readily apparent.That is, when light from source A falls on the mirror D it will bereflected to one of the cells, H, for example, thereafter to impinge onthe other cells, H, H* and H in succession.

As the light is cut ofl each cell for threefourths of the total time,each cell has a corresponding time in which to recover its originalsensitivity, and, therefore, the resultant phase amplitude on theamplifier is maximum;

It is also quite well understood that can cell passes but a very smallcurrent, and if the arrangement takes off of each cell its peak currentthe maximum total current available is materially increased.

Obviously, it is not necessary to limit the mechamsm to that shownherein, for other schemes may be employed for connecting the cells tothe outlet circuit.

.What I claim, is-

1. In apparatus of the class described, the combination of a pluralityof fixedly-la 'cated light-sensitive cells, a light source, an apertureof approximately equal dimensions 111 ri ht angle directions and locatedbetween the light source and the cells, and a continuously rotatingmirror for directing said light to each sensitive cell in succession.

2. In apparatus of the class described, the 1 combination of a pluralityof fixedly-located light-sensitive cells, a light source, an aperturebetween .the light source and the cells, and a continuously rotatinmirror for directing said light to each said cells in suc- 5 cession.

3. In apparatus of the class described, the combination of a pluralityof fixedly-located light-sensitive cells, a light source, and a continuously rotating mirror for directing said light to each said cells insuccession. 10

In testimony whereof I have aflixed my signature.

CHARLES FRANCIS JENKINS.

